Next Article in Journal
Synthesis, Crystal Structure, and Chemical-Bonding Analysis of BaZn(NCN)2
Next Article in Special Issue
Modification of TiO2 Surface by Disilanylene Polymers and Application to Dye-Sensitized Solar Cells
Previous Article in Journal
Field-Induced Single-Ion Magnet Behaviour in Two New Cobalt(II) Coordination Polymers with 2,4,6-Tris(4-pyridyl)-1,3,5-triazine
Previous Article in Special Issue
Molecular Structures of Enantiomerically-Pure (S)-2-(Triphenylsilyl)- and (S)-2-(Methyldiphenylsilyl)pyrrolidinium Salts
Article Menu
Issue 4 (December) cover image

Export Article

Open AccessArticle

The Silacyclobutene Ring: An Indicator of Triplet State Baird-Aromaticity

Department of Chemistry—BMC, Uppsala University, Box 576, SE-751 23 Uppsala, Sweden
Department of Chemistry-Ångström Laboratory Uppsala University, Box 523, SE-751 20 Uppsala, Sweden
Author to whom correspondence should be addressed.
Inorganics 2017, 5(4), 91;
Received: 23 October 2017 / Revised: 8 December 2017 / Accepted: 11 December 2017 / Published: 15 December 2017
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
PDF [3484 KB, uploaded 15 December 2017]


Baird’s rule tells that the electron counts for aromaticity and antiaromaticity in the first ππ* triplet and singlet excited states (T1 and S1) are opposite to those in the ground state (S0). Our hypothesis is that a silacyclobutene (SCB) ring fused with a [4n]annulene will remain closed in the T1 state so as to retain T1 aromaticity of the annulene while it will ring-open when fused to a [4n + 2]annulene in order to alleviate T1 antiaromaticity. This feature should allow the SCB ring to function as an indicator for triplet state aromaticity. Quantum chemical calculations of energy and (anti)aromaticity changes along the reaction paths in the T1 state support our hypothesis. The SCB ring should indicate T1 aromaticity of [4n]annulenes by being photoinert except when fused to cyclobutadiene, where it ring-opens due to ring-strain relief. View Full-Text
Keywords: Baird’s rule; computational chemistry; excited state aromaticity; Photostability Baird’s rule; computational chemistry; excited state aromaticity; Photostability

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Supplementary material

Printed Edition Available!
A printed edition of this Special Issue is available here.

Share & Cite This Article

MDPI and ACS Style

Ayub, R.; Jorner, K.; Ottosson, H. The Silacyclobutene Ring: An Indicator of Triplet State Baird-Aromaticity. Inorganics 2017, 5, 91.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Inorganics EISSN 2304-6740 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top